{ "number": 812, "headline": "December 10, 2025 Wednesday Evening Winter Weather", "standfirst": "Extreme cold this weekend across Midwest will flood off East Coast", "desk": "winter", "dateline": { "place": "Weather Trader", "state": null, "lat": null, "lon": null, "site_key": null, "site_name": null, "site_url": null, "accent": null }, "edition": "2025-12-11", "published": "2025-12-11T00:17:33.745000Z", "updated": null, "access": "free", "body_html": "
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This is post number 812: Good evening to new subscribers and visitors!

Author: Dr. Ryan Maue (X @RyanMaue X @weathertrader)

Headlines Wednesday Evening

  1. AP News Coverage of Atmospheric River \u2014> Blend of unusual weather conditions brings trillions of gallons in persistent rain to the Northwest

    These storms \u201chave been supercharged by the chain of events that began two weeks ago\u201d much farther west than Hawaii, Maue said. \u2014> MJO

  2. Still watching an Alberta Clipper as it scoots off New England will develop into a stronger storm system that could have enough moisture and proximity to the coast to drop a significant band of snowfall Sunday \u2014 Monday.

  3. Atmospheric river events into the Pacific Northwest \u2014> boatloads of precipitation

  4. Strong Western U.S. ridge remains anchored \u2014 and firmly in charge for the next 10-14 days (at least) \u2014 and this ridging will expand eastward to block off the Arctic air in Canada likely into Christmas \u2014 but there is plenty of time for this plan to fall apart. Indeed, the ridge would be weakest in the Great Lakes and Northeast allowing for the polar vortex lobes to sideswipe a huge population.

  5. VERY COLD \u2014 this weekend across the Midwest/Great Lakes peaking this Sunday.

California Central Valley STILL socked in with low clouds and fog/mist with very cool temperatures (40s) due to high pressure induced inversion layer \u2014 similar to the \u201cwedge\u201d that we see in Atlanta from easterly flow across the Appalachians

Current Frontal Boundaries and Weather into Thursday morning

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HRRR 18z | Next 48-Hours through Thursday 1 PM ET

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Precipitation Type | Weather Next 10-days | ECMWF 12z

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Storm track is up and over the western ridge \u2014> so anything that develops has difficulty tapping into Gulf of Mexico or Subtropical Pacific moisture feeds

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Low Temperatures Next 9-days | Until Friday, Dec 19th

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Coldest mornings will be Sat/Sun/Mon across the Midwest and Great Lakes including Chicago at -4\u00b0F

ECMWF 18z Precipitable Water Next 6-days | My favorite parameter

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A zonally oriented atmospheric river system will pour huge plume of moisture into the Pacific Northwest. The Cascades and Rocky Mountains extract most of the moisture but some does cross into the Midwest to feed the parade of Alberta Clippers.

Temperatures | Current to Next 15-days

Temperature Anomaly | Next 15-days

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Flagship European model ensemble solution for temperature anomaly next 15-days

Into Days 10-15, the cold pool retracts into Alaska as the number of members with strong Lower 48 ridging increases \u2014 completely wiping out the Arctic cold influence. But we\u2019ll need to watch the advance/retreat along the Canadian Border to see if this ridge can hold firm.

Temperature Anomaly Next 6-days | Into Saturday afternoon

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Exceptionally cold air spills into the Midwest and Great Lakes into this weekend, but warmer air from the Southwest and Gulf of Mexico battles back \u2014> Light at the end of the tunnel

RTMA | Current Temperature Analysis | 5:45 PM ET

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Average Lower 48 temperature was 46.0\u00b0F

Temperature Anomaly | 5:45 PM ET

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Lower 48 Temperature Anomaly was 6.9\u00b0F ABOVE normal

Thursday Morning Low Temperatures

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174 million below freezing (Lower 48 average low is 30.8\u00b0F)

Thursday High Temperatures

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Warming trend continues as 56% of the Lower 48 by area > 50\u00b0F and we do have almost 50 million population at least 70\u00b0F

Sunday Low Temperatures | Arctic Blast Peak in Midwest + Great Lakes

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Frigid across the Midwest \u2014> colder than -20\u00b0F over Iowa, Minnesota, and the Dakotas

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Chicago potential for two subzero mornings (Sunday -4\u00b0F and Monday 0\u00b0F)

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Upper 70s to lower 80s in Miami through next 10-days

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NWS Precipitation Next 72-hours

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NWS Snowfall Next 72-hours

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Blend of Models | 10 Days Precipitation Total

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Blend of Models | Total Snowfall Next 10-Days

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ECMWF AIFS-Single 12z | Height Anomaly (500 hPa) Next 10-days

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Even with the strong ridging across the Western U.S. the Northeast sees enough of a weakness to let \u201cPolar Vortex\u201d origin troughs to reach the Lower 48 \u2014 with cold air \u2014 so this \u201cBlow Torch\u201d pattern has the potential to be eroded at the margins \u2014> but since that\u2019s where so many people live in New England, surprise heating degree days could show up out of the blue (or the ensemble mean)

Day 10 \u2014> see the potential for a Northeast major trough (!)

NOAA AI-GFS 18z | 500 mb Temperature | Next 10-days

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The main \u201cpolar vortex\u201d centroid is anchored over Hudson Bay \u2014> 50\u00b0C intensity at 500 mb

Dynamic Tropopause Day 8 Little White Fuzzball

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Day 10 | 500 mb Height Anomaly from ECMWF AI/Full Physics Products

ECMWF 12z | Integrated Vapor Transport Next 10-days | North America

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Parameter used for monitoring \u201catmospheric rivers\u201d usually along the U.S. west coast, but the idea works well for many other areas \u2014 highlighting midlatitude storm systems with warm conveyor belts (moisture plumes)

ECMWF 18z | Snowfall | Next 6-days

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Watching with significant interest \u2014> 4\u201d-8\u201d in NYC to Boston from sneaky coastal storm!

ECMWF EPS 12z | Ensemble Median Snowfall Next 15-days

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ECMWF EPS 12z | Ensemble Maximum Snowfall Next 15-days

Worst possible case for entire 51-member ensembles.

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ECMWF EPS 12z | Ensemble Snowfall Probability > 1\u201d | Next 15-days

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We\u2019ll be monitoring the 1\u201d chance of snowfall for a \u201cWhite Christmas\u201d in the coming weeks. This map is morning December 25th.

ECMWF EPS 12z | Ensemble Snowfall Probability > 6\u201d | Next 15-days

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6-inches is sufficient for a \u201cbig storm\u201d and Lake Effect machine diagnostic

Next 15-days Temperature Anomaly | Ensemble Mean to December 24

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The western ridge is STRONG \u2026 and should provide enough Pacific moisture and moderating mild air to temper the longevity and intensity of any Arctic blasts that sink from the massive cold pool over Western Canada.

Temperature Anomaly | Next 15-days | ECMWF EPS 12z

5-Day Chunk #1 | Temperature Anomaly | Dec 10 - Dec 14

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5-Day Chunk #2 | Temperature Anomaly | Dec 15 - Dec 19

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5-Day Chunk #3 | Temperature Anomaly | Dec 20 - Dec 24

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Way, way below normal cold-pool lurks in Western Canada and Alaska.

Comparison with 5-Day Chunk #3 from the 00z EPS cycle

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5-day Difference between the previous cycle

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Note, we\u2019ll be watching the Canadian border in the coming days.

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", "body_key": null, "teaser_html": "

AP News Coverage of Atmospheric River \u2014> Blend of unusual weather conditions brings trillions of gallons in persistent rain to the Northwest

These storms \u201chave been supercharged by the chain of events that began two weeks ago\u201d much farther west than Hawaii, Maue said. \u2014> MJO

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